Zinc and taurine in Friedreich's ataxia.

Zinc and taurine were measured in urine in the fasting state and following a 4mg/kg load of taurine in subjects with Friedreich's Ataxia (FA), and healthy controls (C), and subjects with Duchenne type muscular dystrophy (MD). Of the FA, 25% had increased fasting excretion of zinc, and 50% had increased excretion of zinc following the taurine load. The MD subjects all had increased zinc excretion at all times. The increased zinc excretion did not correlate with increased excretion of taurine. As an index of zinc deficiency, uptake of zinc by erythrocytes was measured in all subjects and in heterozygotes for FA. The pattern of uptake was abnormal for FA and heterozygotes. Hair analysis for zinc showed that 10 of the 12 FA subjects had low values. We conclude that significant abnormalities in zinc metabolism exist in some, but not all cases of FA. The evidence available does not permit definition of the cause of these abnormalities, whether zinc deficiency or abnormal zinc transport is the primary factor.